Watson picked up on a blog post by web developer Mischa Tuffield, of online identity protection firm Garlik, which explains how Google Analytics and Webtrends are used to track behaviour on the site.

He writes: “If this was a website about pub reviews these third-party services would be acceptable, but due to the nature of the information on the Choices website, I feel the NHS should be hosting their own analytics code.”

Tuffield also raises privacy concerns about the site’s use of the Facebook ‘Like’ button and the Add This social media sharing function. He says he has written to the NHS to complain, while MP Watson tweeted: “Whoa! Thks to ppl who raised this NHS tracking story: http://bit.ly/9MlvUY will get on it fast, today.”

The privacy policy on the NHS website explains that cookies are used to track site behaviour, although it says “the cookies we use identify you merely as a number”.

It adds: “When visiting NHS Choices pages that display a Facebook Like button, information relating to the date and time of your visit, the web page you are on (commonly known as the URL) and other technical information about the IP address, browser and operating system you use will be collected by Facebook. If you are logged into Facebook, your user ID number will also be associated with the information mentioned above.”

Tuffield says: “This intrusive opt-out method of adding social features to the NHS website, in my opinion, is not acceptable.”